Search for the Critical Point of Quantum Chromodynamics (QCD)

寻找量子色动力学（QCD）的临界点

• 批准号: 34261596
• 负责人: Professor Dr. Reinhard Stock
• 金额: --
• 依托单位: Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/34261596?language=en
• 关键词: Search; Critical; Point; Quantum; Chromodynamics

Relativistic nucleus-nucleus collisions create a short-lived compound system (the Hagedorn fireball) of fused, high energy density matter, the properties of which being reflected in a multitude of physics observable as imbedded in the experimentally observed final state. A recent breakthrough in non-perturbative lattice Quantum Chrome-dynamics (QCD) has led to detailed predictions concerning the parton-hadron coexistence line in the QCD phase diagram which, in particular, seems to exhibit a critical point in the (, T-diagram. Moreover (pending further lattice technical refinement) this point appears to occur in the interval 300 ( (B ( 450 MeV that corresponds to the lower energy domain of the CERN SPS experiments (7 ( ( 10 GeV) that ended in 2002. The renewed interest in this energy interval leads us to propose revisting the corresponding NA49 data (Pb+Pb at various SPS energies) which either have not been previously analyzed, or are not yet in their final form. The physics of the critical point (and the first order parton hadron phase transition occurring at ( > (crit) suggest event by event fluctuation analysis, e.g. of the eventwise transverse momentum < pT >, the pion and kaon multiplicity density, as well as several ratios of nonstrange to strange particle production like the eventwise K/( and K/p ratios. The large acceptance and the high hadron discrimination power of NA49 (which ran until 2002) make these data analysis particularly promising.

相对论性的核-核碰撞产生了一个短寿命的混合系统（哈格多恩火球），融合了高能量密度的物质，其特性反映在实验观察到的最终状态中可观察到的大量物理现象中。最近在非微扰晶格量子铬动力学（QCD）上的一个突破导致了对QCD相图中部分-强子共存线的详细预测，特别是在t图中似乎表现出一个临界点。此外（有待进一步的晶格技术改进），这一点似乎发生在300 (B) 450 MeV区间，对应于2002年结束的欧洲核子研究中心SPS实验(7 （10 GeV）的较低能量域。对这一能量区间的重新关注使我们提出重新审视相应的NA49数据（Pb+Pb在各种SPS能量下），这些数据要么以前没有被分析过，要么还没有形成最终形式。在临界时刻（>）发生的临界点（和一阶部分强子相变）的物理特性建议对事件进行事件涨落分析，例如，事件方向横向动量< pT >，介子和介子多重密度，以及非奇异粒子与奇异粒子产生的几种比率，如事件方向K/（和K/p比率）。NA49（一直持续到2002年）的高接受度和高强子辨别能力使得这些数据分析特别有前景。